unit AsphyreData;
//---------------------------------------------------------------------------
// AsphyreData.pas                                      Modified: 12-Jul-2005
// Data Compression and CRC32 routines                           Version 1.01
//---------------------------------------------------------------------------
// The contents of this file are subject to the Mozilla Public License
// Version 1.1 (the "License"); you may not use this file except in
// compliance with the License. You may obtain a copy of the License at
// http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS"
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
// License for the specific language governing rights and limitations
// under the License.
//---------------------------------------------------------------------------
interface

//---------------------------------------------------------------------------
uses
 Types, Classes, AsphyreZLib;

//---------------------------------------------------------------------------
type
 TCompressionLevel = (clLowest, clNormal, clHighest);

//---------------------------------------------------------------------------
// DataChecksum()
//
// Calculates a CRC32 checksum of the specified data.
// Originally written by Earl F. Glynn, 1999 (?)
//---------------------------------------------------------------------------
function DataChecksum(Source: Pointer; Size: Integer): Longword;

//---------------------------------------------------------------------------
// CompressData()
//
// Compresses a given number of bytes of source data and saves the compressed
// data in the destination address. The output size can be limited by
// specifying non-zero value in "MaxDestSize".
//---------------------------------------------------------------------------
function CompressData(Source, Dest: Pointer; SourceSize,
 MaxDestSize: Cardinal; Compression: TCompressionLevel = clNormal): Integer;

//---------------------------------------------------------------------------
// DecompressData()
//
// Decompresses the previously compressed data (by InflateData routine) and
// saves it in the destination address. The output size can be limited by
// specifying non-zero value in "MaxDestSize".
//---------------------------------------------------------------------------
function DecompressData(Source, Dest: Pointer; SourceSize,
 MaxDestSize: Cardinal): Integer;

//---------------------------------------------------------------------------
implementation

//---------------------------------------------------------------------------
const
 LookupCRC32: array[0..255] of Longword =
  ($00000000, $77073096, $EE0E612C, $990951BA, $076DC419, $706AF48F, $E963A535,
   $9E6495A3, $0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988, $09B64C2B, $7EB17CBD,
   $E7B82D07, $90BF1D91, $1DB71064, $6AB020F2, $F3B97148, $84BE41DE, $1ADAD47D,
   $6DDDE4EB, $F4D4B551, $83D385C7, $136C9856, $646BA8C0, $FD62F97A, $8A65C9EC,
   $14015C4F, $63066CD9, $FA0F3D63, $8D080DF5, $3B6E20C8, $4C69105E, $D56041E4,
   $A2677172, $3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B, $35B5A8FA, $42B2986C,
   $DBBBC9D6, $ACBCF940, $32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59, $26D930AC,
   $51DE003A, $C8D75180, $BFD06116, $21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F,
   $2802B89E, $5F058808, $C60CD9B2, $B10BE924, $2F6F7C87, $58684C11, $C1611DAB,
   $B6662D3D, $76DC4190, $01DB7106, $98D220BC, $EFD5102A, $71B18589, $06B6B51F,
   $9FBFE4A5, $E8B8D433, $7807C9A2, $0F00F934, $9609A88E, $E10E9818, $7F6A0DBB,
   $086D3D2D, $91646C97, $E6635C01, $6B6B51F4, $1C6C6162, $856530D8, $F262004E,
   $6C0695ED, $1B01A57B, $8208F4C1, $F50FC457, $65B0D9C6, $12B7E950, $8BBEB8EA,
   $FCB9887C, $62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65, $4DB26158, $3AB551CE,
   $A3BC0074, $D4BB30E2, $4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB, $4369E96A,
   $346ED9FC, $AD678846, $DA60B8D0, $44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9,
   $5005713C, $270241AA, $BE0B1010, $C90C2086, $5768B525, $206F85B3, $B966D409,
   $CE61E49F, $5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4, $59B33D17, $2EB40D81,
   $B7BD5C3B, $C0BA6CAD, $EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A, $EAD54739,
   $9DD277AF, $04DB2615, $73DC1683, $E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8,
   $E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1, $F00F9344, $8708A3D2, $1E01F268,
   $6906C2FE, $F762575D, $806567CB, $196C3671, $6E6B06E7, $FED41B76, $89D32BE0,
   $10DA7A5A, $67DD4ACC, $F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5, $D6D6A3E8,
   $A1D1937E, $38D8C2C4, $4FDFF252, $D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B,
   $D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60, $DF60EFC3, $A867DF55, $316E8EEF,
   $4669BE79, $CB61B38C, $BC66831A, $256FD2A0, $5268E236, $CC0C7795, $BB0B4703,
   $220216B9, $5505262F, $C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04, $C2D7FFA7,
   $B5D0CF31, $2CD99E8B, $5BDEAE1D, $9B64C2B0, $EC63F226, $756AA39C, $026D930A,
   $9C0906A9, $EB0E363F, $72076785, $05005713, $95BF4A82, $E2B87A14, $7BB12BAE,
   $0CB61B38, $92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21, $86D3D2D4, $F1D4E242,
   $68DDB3F8, $1FDA836E, $81BE16CD, $F6B9265B, $6FB077E1, $18B74777, $88085AE6,
   $FF0F6A70, $66063BCA, $11010B5C, $8F659EFF, $F862AE69, $616BFFD3, $166CCF45,
   $A00AE278, $D70DD2EE, $4E048354, $3903B3C2, $A7672661, $D06016F7, $4969474D,
   $3E6E77DB, $AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0, $A9BCAE53, $DEBB9EC5,
   $47B2CF7F, $30B5FFE9, $BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6, $BAD03605,
   $CDD70693, $54DE5729, $23D967BF, $B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94,
   $B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D);

//---------------------------------------------------------------------------
function DataChecksum(Source: Pointer; Size: Integer): Longword;
var
 pb   : PByte;
 i    : Integer;
 Index: Longword;
begin
 pb:= Source;
 Index:= $FFFFFFFF;
 for i:= 0 to Size - 1 do
  begin
   Index:= (Index shr 8) xor LookupCRC32[pb^ xor (Index and $000000FF)];
   Inc(pb);
  end;

 Result:= not Index;
end;

//---------------------------------------------------------------------------
function CompressData(Source, Dest: Pointer; SourceSize,
 MaxDestSize: Longword; Compression: TCompressionLevel): Integer;
var
 OutBuf  : Pointer;
 DestSize: Integer;
 zLevel  : TZCompressionLevel;
begin
 case Compression of
  clLowest: zLevel:= zcFastest;
  clNormal: zLevel:= zcDefault;
  else zLevel:= zcMax;
 end;

 OutBuf:= nil;
 DestSize:= 0;
 try
  ZCompress(Source, SourceSize, OutBuf, DestSize, zLevel);
 except
  Result:= 0;
  Exit;
 end;
 if (OutBuf = nil) then
  begin
   Result:= 0;
   Exit;
  end else
  begin
   if (Int64(DestSize) <= MaxDestSize) then
    Move(OutBuf^, Dest^, DestSize)
     else Move(OutBuf^, Dest^, MaxDestSize);

   Result:= DestSize;
   FreeMem(OutBuf);
  end;
end;

//---------------------------------------------------------------------------
function DecompressData(Source, Dest: Pointer; SourceSize,
 MaxDestSize: Longword): Integer;
var
 OutBuf  : Pointer;
 DestSize: Integer;
begin
 OutBuf:= nil;
 DestSize:= 0;
 try
  ZDecompress(Source, SourceSize, OutBuf, DestSize);
 except
  Result:= 0;
  Exit;
 end;
 if (OutBuf = nil) then
  begin
   Result:= 0;
   Exit;
  end else
  begin
   if (Int64(DestSize) <= MaxDestSize) then
    Move(OutBuf^, Dest^, DestSize)
     else Move(OutBuf^, Dest^, MaxDestSize);

   Result:= DestSize;
   FreeMem(OutBuf);
  end;
end;

//---------------------------------------------------------------------------
end.
